Foldable lift device



Oct. 14., 1969 J, NAUGHTON 3,472,488

FOLDABLE LIFT DEVI CE Filed July 5, 1967 2 Sheets-Sheet 1 JOHN L Am/w/m/v Oct. 14, 1969 J. L. NAUGHTON FOLDABLE LIFT DEVICE 2 Sheets-Sheet2 Filed July 5, 1967 //v V1VT0A7 Jamv L. Amum/ra/v 5 @z A0. M

47'70F/VEY United States Patent O 3,472,488 FOLDABLE LIFT DEVICE John L.Naughton, Des Moines, Iowa, assignor to Den- Tal-Ez Chair ManufacturingCo., Des Moines, Iowa, a corporation of Iowa Filed July 5, 1967, Ser.No. 651,252 Int. Cl. A47c 3/20; B66f 3/22 US. Cl. 254-122 6 ClaimsABSTRACT OF THE DISCLOSURE The lift device is used for raising andlowering chairs, such as a dental chair and includes a pair oftransversely spaced oppositely arranged upright lazy tong assemblies,each of which has upper and lower pairs of tong members. One of the tongmembers in each lower pair is pivoted at its free end to a base meansand the other lower tong member has its free end movably supported onthe base means for movement longitudinally thereof. A horizontal liftpad for supporting a chair is pivotally connected to the free end of oneof the tong members in each upper pair. The other upper tong member hasits free end movably connected with the lift pad for movement relativeto the pad in a direction longitudinally of the base means. A carriageunit longitudinally movable on the base means carries a lift means at aposition between the lazy tong assemblies. The lift means is attached tothe pivots which connect together the lower pairs of tong members and isguided for vertical up and down movement so that the lazy tongassemblies are vertically extended and retracted in response to the upand down movement of the lift means to raise and lower the lift pad in ahorizontal position therefor.

SUMMARY OF THE INVENTION The lift device of this invention provides forthe raising and lowering of a dental chair between limits such that apatient therein can be comfortably worked upon by a dentist from eithera seated or a standing position. The lift or chair supporting pad at theupper end of the lift device, for all moved positions of the liftdevice, is maintained in a horizontal position and stabilized againsttipping movement out of a horizontal plane. An adjusted position of thechair relative to the pad is thus continuously maintained. The liftdevice operates to efficiently raise and lower a dental chair with apatient therein, and is of a compact construction so as not to interferewith the freedom of movement of the dentist about the chair and may bereadily substituted for the usual supporting base or standard for achair.

DETAILED DESCRIPTION OF THE INVENTION Further objects, features andadvantages of this invention will become apparent from the followingdescription when taken in connection with the accompanying drawing inwhich:

FIG. 1 is a perspective view showing a dental chair in assembly relationwith the lift device of this invention;

FIG. 2 is an enlarged sectional view taken substantially on line 22 inFIG. 1 showing the lift device in side elevation and in a raisedposition therefor;

FIGS. 3, 4, and 6 are detail sectional views as seen on the lines 33,44, 5-5, and 66, respectively, in FIG. 2; and

FIGS. 7 and 8 are diagrammatic side elevational views showing the liftdevice in raised and lowered positions, respectively.

Referring to the drawings, the lift device, indicated generally at 10,is shown in FIG. 1 for use with a contoured dental chair 11. The liftdevice is mounted for rotational movement on a floor plate 12 and isheld in a rotated position by means including a foot actuated lockinglever 13.

The lift device 10 (FIGS. 2 and 5) inclhdes a base member 14 of arectangular shape and a pair of like transversely opposite upright lazytong assemblies 16 sup ported on the base member and having a lift pad17 carried on and extended between the upper ends thereof. The lift pad17 constitutes a mounting plate for the dental chair 11. A lift means,designated generally as 18, is mounted on a movable carriage unit 19 ata position between the lazy tong assemblies 16 and is connected with thetong assemblies 16 to provide for their extension and contraction toraise and lower the lift pad 17.

The base member 14 (FIG. 5) is suitably mounted on and secured to abearing plate 21 that has a depending hub 22 rotatably received withinthe floor plate 12. The carriage unit 19 (FIGS. 2 and 5) is receivedwithin a longitudinally extended guideway 23 formed in the top surfaceof the base member 14 for movement longitudinally of the base member.Supporting rollers 24 on the carriage unit 19 are ridable on the bottomwall 26 of the guideway 23.

Since each of the lazy tong assemblies 16 is of a like construction andoperation only one thereof will be described in detail with likenumerals being applied to corresponding parts. A lazy tong assembly 16includes a lower pair of tong members 27 and 27a (FIG. 2) and a pair ofupper tong members 28 and 28a. The lower tong members 27 and 27a arepivotally connected together at 29 intermediate the ends thereof toprovide for their relative movement in what may be called a scissorsaction. The pivot means 29 (FIG. 5) includes a sleeve bearing 31inserted within aligned openings 32 extended transversely through eachtong member 27 and 27a for receiving a pivot bolt 33 the inner end ofwhich is threadable within a horizontal ring collar 34 located betweenthe pivot means 29 and forming part of the lift means 18. As bestappears in FIG. 2 the sections of the tong members 27 and 27a locatedupwardly from the pivot means 29 are of a shorter length than thesections thereof that are located below the pivot means 29.

The lower end of the tong member 27 (FIGS. 2 and 5) is pivotallyconnected at 36 to one end 37 of the base member 14 for pivotal up anddown movement about an axis extended transversely of the base member.The lower end of the tong member 271; carries a roller 38 operativelyassociated with a track assembly 39 (FIGS. 2 and 3) for movementlongitudinally of the base member 14. Coacting portions on the roller 38and track means 39 maintain the roller 38 against vertical andtransverse movement relative to the base member 14, during movement ofthe roller longitudinally of the base member. It is seen, therefore,that when the tong member 27 is pivoted about the pivot 36, the lowerend of the tong member 27a is concurrently moved longitudinally of thebase member 14 to provide for a scissors action of the tong members 27and 27a.

The upper pair of tong members 28 and 28a are pivotally connectedtogether intermediate their ends by a transversely extended pivotbearing 41.. As seen in FIG. 2 sections of the tong members 28 and 28aupwardly from the pivot 41 are of a shorter length than the sectionsthereof located below the pivot 41. The lower ends of the tong members28 and 28a are connected by transverse pivots 42, with the correspondingupper ends of the lower tong member 27 and 27a.

The lift pad 17 (FIG. 2) includes a horizontal body member 43 that isprovided at one end with a centrally located depending lug 44 of agenerally hook shape. The upper ends of the tong members 28 are bentinwardly toward each other to positions adjacent the opposite sides ofthe lug 44 to which they are pivotally connected by a transverselyextended pivot means 46. Rollers 47 (FIGS. 2 and 4) are carried at theupper ends of the tong members 28a for ridable engagement in a trackmeans 48 provided at the end of the lift pad 17 remote from the pivotmeans 46. The upper ends of the tong members 28a are thus movablerelative to the lift pad 17 in a direction longitudinally of the basemember 14.

It is to be noted that the axes of the rollers 47 are in a horizontalplane common to the axis of the pivot means 46. The lift pad 17 is thusretained in a horizontal plane for all relatively moved positions of thetong members 28 and 28a. In this connection it is also to be noted thatthe axes of the rollers 38 on the tong members 27a are in a horizontalplane common to the axes of the pivots 36 for the tong members 27. Withthe rollers 38 and 47, and the pivot connections 29, 36, 42, 41 and 46in one lazy tong assembly 16 being in coaxial alignment with the likerollers and pivot connections of the other of the lazy tong assemblies16 the axes therefore are always maintained in horizontal planes for allmoved positions of the assemblies 16.

The lift means 18 includes an upright screw shaft 49 (FIGS. and 6)coaxial with the ring collar 34 and having its lower end rotatablysupported in a bearing 51 carried in the top side of the carriage unit19. An upright lower or stationary cylindrical sleeve member 52, in aconcentrically spaced relation about the shaft 49 is formed at thebottom thereof with a laterally extended annular flange 53 for mountingon the top side of the carriage unit 19. The flange 53 is rigidlysecured to the carriage unit by any suitable means such as cap screws 54(FIG. 2).

An outer cylindrical sleeve member 56 (FIG. 5) is in a concentricallyspaced relation about the stationary sleeve member 52 and carries on theinside of its bottom end a ring bearing 57 for slidable bearingengagement with the outer peripheral surface of the stationary sleevemember 52. Opposite the ring bearing 57 and secured to the outsidesurface of the outer sleeve member 56 is a supporting collar 58. Thering collar 34, that is secured to the pivot bolts 33, is in a nestedrelation about the outer sleeve member 56 and rests directly on thesupporting collar 58. A usual friction screw (not shown) is threadablethrough the ring collar 34 and into engagement with the outer sleevemember 56 to retain the ring collar 34 and into engagement with theouter sleeve member 56 to retain the ring collar 34 on the supportingcollar 58.

An inner sleeve member 59 is telescopically received within and inbearing engagement with the inner peripheral surface of the stationarysleeve member 52. Provided within and secured to the sleeve member 59 atits lower end is a lift nut 61 in operative association with the screwshaft 49. The upper portion of the outer sleeve member 56 is formed witha section 62 of a reduced diameter for engaging the upper end of theinner sleeve member 59. The sleeve members 56 and 59 are connectedtogether at their upper ends by screws or the like 63 for concurrentmovement relative to the stationary sleeve member 52.

It is seen, therefore, that the movable sleeve members 56 and 59, duringtheir concurrent movement relative to the lower or stationary sleevemember 52, are continuously guided for vertical movement by virtue oftheir bearing engagement with the inner and outer peripheral surfaces ofthe stationary sleeve member. Since the lift nut 61 is secured to theinner sleeve member 59, and the ring collar 34 is connected to the pivotbolts 33, the lazy tong assemblies 16 are positively guided forextension and contraction in parallel vertical planes to raise and lowerthe lift pad 17. The sleeve assembly 52, 56, and 59 thus functions as astabilizing mechanism to maintain a vertical raising and lowering of thelift pad 17 and a holding of the lift pad in a horizontal plane for allmoved positions thereof.

Rotation of the screw shaft 49 to raise and lower the lift pad 17 isaccomplished by means including a reversible electric motor 64 (FIGS. 2and 6) mounted on the carriage unit 19 to one side of the stationarysleeve member 52. A gear unit 66 operatively associated with the motordrive shaft (not shown) includes a drive sprocket 67 located in thehorizontal plane of a driven sprocket 68 mounted at the lower end of thescrew shaft 49 and connected with the drive sprocket 67 by a sprocketchain 69. The lower end of the stationary sleeve 52 is cut away to formopenings 71 (FIG. 5) to accommodate opposite lengths of the sprocketchain 69. The motor 64 is operated by means including a switch having afoot actuated lever 72 (FIG. 1).

As shown in FIG. 7, on operation of the motor 64 to extend the lazy tongassemblies 16, the tong members 27 are pivoted relative to the pivots 36concurrently with the movement of the lower ends of the tong members 27alongitudinally and inwardly of the base member 14. This relative pivotalmovement of the tong members 27 and 27a takes place by virtue of theelevating of the pivots 29 by the lift nut 61. The relative pivotalmovement of the lower tong members 27 and 27a is in turn transmitted tothe upper pair of tong members 28 and 28a through the pivot connections42. During this relative pivotal movement between the tong members 28and 2811 the tong members 28 pivot relative to the lift pad 17 at thepivot connection 46, and the free ends of the tong members 28a moverelative to the lift pad 17 at the roller and track assembly 47 and 48.The carriage unit 19, stationary cylinder 52 and motor 64 are movedtogether longitudinally of the base member 14 in a direction towards thepivots 36. This movement is indicated in FIG. 7 by the travel of theaxis 73 of the stationary cylinder 52 from its position indicated by thedash line A to a position indicated by the dash line B.

On lowering of the lift pad 17 to a contracted or folded position of thelift device 10 the lazy tong assemblies 16, carriage unit 19 and liftpad 17 are moved to their relative positions shown in FIG. 8.

In one embodiment of the lift device 10, the pad 17, in its loweredposition, is at an elevation of about eleven inches above the floorsurface, and is extendable to a raised position to a height above thefloor surface of about twenty-eight inches. During this lowering andraising of the lift pad 17, the lift device 10 is maintainedsubstantially within the dimensional confines of the base member 14which is about twenty-four inches long and thirteen inches wide. Asshown in FIGS. 1, 2 and 5 the entire lift device 10 is enclosed withinan accordion or bellows type housing 74 having the locking lever 13 andmotor actuating lever 72 projected therefrom at positions convenientlyaccessible for foot actuation.

Although the invention has been described with respect to a preferredembodiment thereof, it is to be understood that it is not to be solimited since changes can be made therein which are within the fullintended scope of this invention as defined by the appended claims.

I claim:

1. A lift apparatus comprising:

(a) a base means,

(b) a pair of upright transversely opposite aligned lazy tong assemblieseach of which includes upper and lower pairs of tong members, with onetong member of each lower pair of tong members pivotally connected atone end to said base means, and the other tong member of each lower pairof tong members movably supported at one end on the base means formovement longitudinally thereof,

(0) a lift pad,

(d) a first tong member of each upper pair of tong members pivotallyconnected at one end to said lift pad, and the second tong member ofeach upper pair of tong members movably connected at one end to saidlift pad for movement relative thereto in a direction longitudinally ofsaid base means,

(e) a carriage structure supported on said base means for movementlongitudinally thereof,

(f) a vertically movable lift means mounted on said carriage meansintermediate said pair of lazy tong assemblies, and

(g) means connecting said pair of lazy tong assemblies to said liftmeans for vertical movement to unfolded and folded positions therefor inresponse to up and down movement, respectively, of said lift means.

2. A lift apparatus according to claim 1 wherein:

(a) said lift means is connected to each of said lower pair of tongmembers and located within the vertical height of said lazy tongassemblies when said assemblies are in either the folded position or theunfolded position therefor.

3. A lift apparatus comprising:

(a) base means,

(b) a pair of like transversely spaced lazy tong assemblies, with all ofthe pivot connections connecting together the tong members in one ofsaid assemblies being in coaxial alignment with all of the correspondingpivot connections in the other of said assemblies, each of saidassemblies including upper and lower pairs of tong members,

(0) a lift pad,

(d) a first tong member in each upper of tong members pivotallyconnected at one end to said lift pad and the second tong member in eachupper pair of tong members movably connected at one end to said lift padfor movement relative thereto in a direction longitudinally of said basemeans,

(e) a carriage unit movably supported on said base means for movementlongitudinally thereof,

(f) a first tong member in each lower pair of tong members pivotallyconnected at one end to said base means, and the second tong member ineach lower pair of tong members movably supported at one end on saidbase means for movement longitudinally thereof,

(g) vertically movable lift means mounted on said carriage unitintermediate said tong assemblies, and (h) means connecting a pair ofsaid coaxially aligned pivot connections to said lift means forvertically movement of said tong assemblies to unfolded and foldedpositions therefor in response to up and down movement, respectively, ofsaid lift means.

4. A lift apparatus according to claim 3 wherein:

(a) said lift means includes an upright screw shaft rotatably supportedon said carriage unit,

(b) a lift nut for said screw shaft connected to said pair of coaxiallyaligned pivot connections, and

(c) a reversible motor means mounted on said base means in a drivingrelation with said screw shaft.

5. A lift apparatus according to claim 4 including:

(a) a vertically extended telescoping means mounted on said carriageunit and guidably associated with said lift nut to stabilize the liftnut for vertical travel on said screw shaft.

6. A lift apparatus according to claim 5 wherein said verticallyextended telescoping means includes:

(a) a first upright cylindrical sleeve member mounted on said carriageunit in a concentrically spaced relation about said screw shaft,

(b) an inner cylindrical sleeve member telescopically received withinsaid first sleeve member in bearing engagement therewith,

(c) an outer cylindrical sleeve member for telescopically receiving saidfirst sleeve member in bearing engagement therein,

(d) means connecting together the upper ends of said inner and outersleeve members for concurrent movement axially of said first sleevemember,

(e) means rigidly connecting said lift nut to the lower end of saidinner sleeve member in coaxial alignment with said three sleeve members,and

(f) means adjacent the lower end of said outer sleeve member connectedto said pair of coaxially aligned pivot connections.

References Cited UNITED STATES PATENTS 956,189 4/1910 Schwarz 187-18ROBERT C. RIORDON, Primary Examiner D. R. MELTON, Assistant ExaminerU.S. Cl. X.R.

